Apart from errors in javascript or html, which we can not do much to warn you about, there are some things that might regularly bite the unwary or careless.

Length of colNames <> colModel or 0!

The problem is in the grid definition: the number of columns defined in colNames is not the same as the number of columns defined in colModel -- you've probably added a new column to the colModel and forgotten to add it to colNames.

Expected ]

If this refers to your colNames line, you've probably missed a quote mark around one of the names.

'ts.p.colModel[...].align' is null or not an object

This one means you are sending too many columns of data from the server. If you send too few, then the grid will appear but one or more columns may be missing with data showing up in the wrong column; if you have more hidden fields then missing columns, you might not see this effect until you edit a row and see that one or more fields are not showing up there.